B4R Question 5v Pin?

ilan · Jun 8, 2022

hi

i have a "stupid" question. i see some tutorials that show how to power the arduino board from the 5v pin but then i also see tutorials like this one:

Controlled DC Motor Car with BlueTooth using L298N motor Driver [B4A and B4R]

Hi, This is my first creation for B4R and B4A. Thanks for the community on this forum which I learn much from. I know this is not first creation/stuff that people built, many of controlled DC motor car with bluetooth that already built out there. But the interesting part is I'm using B4A and...

www.b4x.com

that use the 5v pin to power a bluetooth controller and now i am a little bit confused. it the 5v pin to power other device (out) or to power the arduino for an external power supply (in)?

thanx

klaus · Jun 9, 2022

Do not confuse the Vin and 5V pins.
You can supply the Arduino either through the:
- DC power jack (7 - 12V)
- USB connector (5V)
- Vin pin of the board (7-12V)
The 5V pin is a regulated 5V output to supply other elements like sensors, displays or bluetooth modules etc.
Some sensors or elements need a 3.3V supply, for this you can use the 3.3V pin.

If you supply the Arduino via a power jack, you can access this power through the Vin pin for other usage, like a motor.

barx · Jun 8, 2022

You technically can power the board with 5v pin, but it bypasses the regulator, so you need to make sure you have a pretty stable 5v. As the 5v pin it tapped to the output of the regulator, if supplying power through power ports or Vin (before regulator), you can indeed also use 5v pin to power other things. just be careful not to power hungry things.

ilan · Jun 9, 2022

thanx @barx. i read now that the 5v pin is meant to give power and not power the arduino board. and the vin pin is to supply 5v to the arduino before the regulator. so it can demage the board if i connect a higher voltage then 5v to the vin pin. is that correct?

What are the 5V and VIN pins for?

I believe I can supply the Arduino with power in three different ways: Use USB. The design trusts the 5V to be regulated, and does not regulate it in any way. Use a regulated power source, trust...

arduino.stackexchange.com

so 5v pin to supply 5volt to other components and vin is to supply 5v to the arduino and power him with it. is that correct?

thanx

Filippo · Jun 9, 2022

The 5v-pin you can use for both thing.
In my circuits I use the usb-voltage(5 Volt) for Arduino and at the same time for other devices.

ilan · Jun 9, 2022

Filippo said:
The 5v-pin you can use for both thing.
In my circuits I use the usb-voltage(5 Volt) for Arduino and at the same time for other devices.

so you also power the arduino and also power other components at the same time?
and all from the 5v pin (without connecting the arduino via usb or power supply)?

tigrot · Jun 9, 2022

ilan said:
so you also power the arduino and also power other components at the same time?
and all from the 5v pin (without connecting the arduino via usb or power supply)?

If you do both you lose the function of the internal regulator when present. And using the same pin for in and out has no meaning. A better enginered power line can void a mess of problems.

ilan · Jun 9, 2022

hmmm... i am a little bit confused now. what is the intended use of those pins.

5v pin - power components or power arduino?
vin pin ?

it is better not to write all possibilities what i could with them just what is the best usage for them. 5v to ... and vin to ....

thank you guys for your help

Filippo · Jun 9, 2022

Here is a small example:

klaus · Jun 9, 2022

From the Arduino documentation:
The power pins are as follows:

Vin. The input voltage to the Arduino board when it's using an external power source (as opposed to 5 volts from the USB connection or other regulated power source). You can supply voltage through this pin, or, if supplying voltage via the power jack, access it through this pin.
5V.This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7 - 12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it.
3V3. A 3.3 volt supply generated by the on-board regulator. Maximum current draw is 50 mA.
GND. Ground pins.

The 5V pin is a 5V output pin to supply other elements, the same for the 3.3V pin.
To power the Arduino you should use the Vin pin or the two others as specified above.

Filippo · Jun 9, 2022

The 5V pin is a 5V output pin to supply other elements, the same for the 3.3V pin.
To power the Arduino you should use the Vin pin or the two others as specified above.

Hi Klaus,

I use Arduino-Nano for more than 10 years and the 5V pin I always use as input with USB voltage.
Only when I need a higher voltage (e.g. 9 volts) I use the Vin pin.

klaus · Jun 9, 2022

Filippo said:
... and the 5V pin I always use as input with USB voltage.

What do you mean with this?
Are you applying an external 5V supply to the 5V pin as the Arduino power supply ? This is not recommended, even if it might work.
Or do you supply the Arduino via the USB connector and use the 5V pin to supply other elements ? This is the purpose of the 5V pin
I give the answer according to the documentation of the manufacturer.

Filippo · Jun 9, 2022

klaus said:
What do you mean with this?
Are you applying an external 5V supply to the 5V pin as the Arduino power supply ? This is not recommended, even if it might work.
Or do you supply the Arduino via the USB connector and use the 5V pin to supply other elements ? This is the purpose of the 5V pin
I give the answer according to the documentation of the manufacturer.

See my sketch above in post 8. This is exactly how I use it.
I've used it on thousands of Adruino Nano's with no problems.

ilan · Jun 9, 2022

klaus said:
What do you mean with this?
Are you applying an external 5V supply to the 5V pin as the Arduino power supply ? This is not recommended, even if it might work.
Or do you supply the Arduino via the USB connector and use the 5V pin to supply other elements ? This is the purpose of the 5V pin
I give the answer according to the documentation of the manufacturer.

according to the sketch @Filippo is supplying the 5v pin with external power supply to power the arduino.
the motor is also taking the power from the external power supply since it is connected to the same wire so it is not taking the power from the 5v pin.
as far as i understand. it is a parallel connection where the arduino and the motor are connected parallel to the power supply

klaus · Jun 9, 2022

Well, I do not want to give any advice against the recommendations of the manufacturer, even if it works.
That's all.

ilan · Jun 9, 2022

klaus said:
Well, I do not want to give any advice against the recommendations of the manufacturer, even if it works.
That's all.

thanx klaus.

if i read what you wrote (as recommended by the Arduino team) i have still problems to fully understanding it. i guess it is because my English is very poor.

Vin. The input voltage to the Arduino board when it's using an external power source (as opposed to 5 volts from the USB connection or other regulated power source). You can supply voltage through this pin, or, if supplying voltage via the power jack, access it through this pin.

i dont understand the last part. "You can supply voltage through this pin OR IF supplying voltage via the POWER JACK, access it through this pin"
if i supply voltage via power jack then i have already power for the arduino so what does it mean "access it through this pin" does it also act like a output voltage pin so i can also get power from this pin to power other components? (if i use an external power supply that is connected to the power jack")

sorry if my questions are "stupid" ?
i just want to fully understand it

thanx

klaus · Jun 9, 2022

Do not confuse the Vin and 5V pins.
You can supply the Arduino either through the:
- DC power jack (7 - 12V)
- USB connector (5V)
- Vin pin of the board (7-12V)
The 5V pin is a regulated 5V output to supply other elements like sensors, displays or bluetooth modules etc.
Some sensors or elements need a 3.3V supply, for this you can use the 3.3V pin.

If you supply the Arduino via a power jack, you can access this power through the Vin pin for other usage, like a motor.

ilan · Jun 9, 2022

klaus said:
Do not confuse the Vin and 5V pins.
You can supply the Arduino either through the:
- DC power jack (7 - 12V)
- USB connector (5V)
- Vin pin of the board (7-12V)
The 5V pin is a regulated 5V output to supply other elements like sensors, displays or bluetooth modules etc.
Some sensors or elements need a 3.3V supply, for this you can use the 3.3V pin.

If you supply the Arduino via a power jack, you can access this power through the Vin pin for other usage, like a motor.

super clear now. Thank you very much Klaus!!!!! ? ? ?

Filippo · Jun 9, 2022

That should also be clear, right?

klaus · Jun 9, 2022

I was looking at the Arduino UNO documentation.
So, we see that with different boards there are differences.
Therefore the rtfm principle is still a good advice !

Cableguy · Jun 9, 2022

From the arduino uno schematics you can see that the 5V is somewhat of a common rail... that can be used as both power in or out.
The main difference is, no protection whatsoever if used as power in, so the risk of bricking the board are well higher than using the appropriate input.

B4R Question 5v Pin?

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